Research On Output Feedback And Output Regulation For Discrete System With Input Saturation

Nonlinear constraints generally exist in control systems, and saturated nonlinearity is one ofthe most commonly encountered nonlinearity in the control systems. The performance of controlsystems subject to nonlinear constraints could be seriously influenced, and it can debase theperformance. What’s worse, it can lead the closed-loop system to be unstable. Therefore, it isnecessary to research the saturated control systems and has important theoretical significance andbroad application prospect.Having reviewed and concluded the development process and research status on constrainedsystems at home and abroad, this paper mainly studies the following problems and presents thecorresponding conclusion.1. The precise characterization of controllable regions and finite-step controllable region is afundamental problem that must be solved to the constrained model. The purpose of thecharacterization of exact finite-step controllable state set is to design effective control algorithm ofthe systems with input saturation. Based on the exact description of finite-step controllable region,the output feedback problems of linear discrete-time system with input saturation are discussed. Inmost application systems, the states are not directly measured. Therefore, it is necessary to constructan appropriate state observer using the state variables that can be measured and system’s output.Considering unstable systems, the classical implementation method of observer-based outputfeedback is conservative. In order to reduce the conservation of controllable region’s estimation, anew implementation method of output feedback is proposed in this paper, which ensures the closed–loop stability and makes the system’s controllable domain as big as possible.2. Recently, a lot of scholars at home and abroad do deeply research on the output regulationproblem. Considering the robust output regulation problem, we focus on the exogenous signals thatare linear neutral and stable. When it comes to the exosystem is nonlinear, the existing work has notreceived enough attention. Firstly, this paper studies the output regulation problem of saturateddiscrete systems under the action of linear exosystem and then shows the internal model principleand the asymptotically regulable region, on the basic of which a simple feedback controller basedon the stabilizing law to ensure exponential output regulation is designed. Then the outputregulation problem is studied under the action of nonlinear exosystem and cites the square wave andtriangle wave as examples to give the nonlinear internal model and the asymptotically regulableregion. Besides the designed method of state feedback controller is proposed. Finally, the simulationresults demonstrate that the proposed algorithm is effective.